Patent GB-1131889-A (GB)
Title: Improvements in or relating to sorting machines
IPC: B65G47/50
Filed: 1966-10-14
Abstract: 1,131,889. Photo-electric sorting apparatus. MANDREL INDUSTRIES Inc. Oct. 14, 1966 [Oct. 15, 1965], No.46101/66. Heading G1A. [Also in Division G5] In apparatus for sorting objects such as beans, nuts &c., a rotating conveyer wheel 18 successively picking up the objects to be sorted by suction on to ferrules 21, carries the objects through a photoelectric inspection location 59 where the photodetector output is compared with a predetermined level to decide whether the object is defective or acceptable. If the former, a "reject" pulse is recorded on a magnetic drum 52 by a recording head 57 the drum rotating in synchronism with the conveyer wheel 18. This pulse is read out later by a magnetic pick-up head 62 when the object to be rejected is aligned with the "defective" chute, and the ejector mechanism (an air jet 36) actuated. No pulses are stored for acceptable objects which are ejected automatically into the "acceptable" chute after they have passed the "defective" chute. A high-pressure air jet cleans the ferrules after ejection of the objects, and a magnetic erase head 63 removes any pulses, representative of defective objects, from the magnetic drums 52. A further inspection head 61 and recording head 58 may be provided if a further property besides colour is to be investigated. Either or both inspection heads may be operative. When both are operative the pulse recorded on a drum by the further recording head 58 is superimposed on that recorded by head 57. Instead of an electromagnetic radiation inspection head, one utilizing nuclear radiation could be used. Pulses from the inspection heads 59, 61 amplified by amplifiers 68, 69 and representing defective objects, can be transmitted through the voltage detectors 71, 72 to recording heads 57, 58 only while these detectors are gated on by pulses from a reference pulse generator drum 53. This is a permanently magnetized spur gear 53 having two magnetic pick-ups 66, 67 each corresponding to an inspection system. The grooves in gear 53, which revolves in time with the conveyer wheel 18, represent the ferrules of the latter. Thus synchronizing pulses are provided by which recording and read-out of "reject" pulses are correctly synchronized with the location of ferrules. A more sophisticated system is provided, Fig. 3 (not shown), by which conveyer wheels with different numbers of ferrules can be accommodated in the apparatus. In this system, the magnetic drum (52), the reference pulse-generator drum (53) and a further reference drum (53'), having a different number of notches, are mounted on a common shaft driven at three times the rate of the conveyer wheel (18). The output of a pick-up associated with a reference pulse generator drum is fed through a selected part of a counter circuit, to produce the reference pulse rate required for a particular conveyer wheel. The circuit includes an arrangement to reduce drift in the amplifiers (68, 69) associated with the inspection heads and especially drift due to vairation in light intensity. This arrangement includes a permanent magnet (123) attached to the ferrule wheel which produces output pulses from associated pick-ups (121, 122) once each revolution. These pulses close normalizer switches (113, 114) to connect the amplifier circuits to fixed D.C. levels and thus compensate for drift. The pick-ups (121, 122) associated with the permanent magnet also provide periodic pulses to reset the counters in the reference pulse production circuit, to prevent malfunction due to the picking-up of stray pulses by this circuit which would otherwise cause mistiming of the whole sorting sequence. The construction of the magnetic memory drum which is housed in association with the reference pulse generator drums (53, 53'), is described, Figs.4, 5 (not shown) [see Division G5]. Reference has been directed by the Comptroller to Specification 1,025,147.